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app-grid-button: decode the icon before the first draw #2

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app-grid-button: decode the icon before the first draw #2

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139 changes: 139 additions & 0 deletions src/app-grid-button.c
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,10 @@ struct _PhoshAppGridButtonPrivate {

gulong favorite_changed_watcher;

/* Icon pre-warming, see warm_icon() */
GCancellable *icon_cancel;
guint icon_warm_id;

GtkWidget *icon;
GtkWidget *popover;
GtkGesture *long_gesture;
Expand Down Expand Up @@ -115,12 +119,133 @@ phosh_app_grid_button_get_property (GObject *object,
}


/*
* Decode the icon before the button is first drawn.
*
* gtk_image_set_from_gicon() defers the load to the first draw, and a
* GtkFlowBox recycles nothing, so without this the first scroll through the
* grid decodes an icon per row it reveals, on the main thread.
*
* Warming GtkIconTheme instead does not work -- every lookup returns a fresh
* GtkIconInfo, so nothing that a load produced is reused. The decoded pixbuf
* has to be kept, which means putting it on the image.
*/
static void
on_icon_loaded (GObject *source, GAsyncResult *res, gpointer data)
{
GtkIconInfo *icon_info = GTK_ICON_INFO (source);
PhoshAppGridButton *self = data;
PhoshAppGridButtonPrivate *priv = phosh_app_grid_button_get_instance_private (self);
g_autoptr (GdkPixbuf) pixbuf = NULL;
g_autoptr (GError) err = NULL;
cairo_surface_t *surface;

pixbuf = gtk_icon_info_load_icon_finish (icon_info, res, &err);
if (pixbuf == NULL) {
if (!g_error_matches (err, G_IO_ERROR, G_IO_ERROR_CANCELLED))
g_debug ("Could not pre-load icon: %s", err->message);
/* The GIcon is still on the image, so GTK falls back to decoding at draw */
goto out;
}

/* A surface, not the pixbuf: the device scale travels with it */
surface = gdk_cairo_surface_create_from_pixbuf (pixbuf,
gtk_widget_get_scale_factor (GTK_WIDGET (self)),
gtk_widget_get_window (GTK_WIDGET (self)));
gtk_image_set_from_surface (GTK_IMAGE (priv->icon), surface);
cairo_surface_destroy (surface);

out:
g_object_unref (self);
}


static gboolean
warm_icon (gpointer data)
{
PhoshAppGridButton *self = data;
PhoshAppGridButtonPrivate *priv = phosh_app_grid_button_get_instance_private (self);
g_autoptr (GtkIconInfo) icon_info = NULL;
GIcon *icon;
int size, scale;

priv->icon_warm_id = 0;

if (priv->info == NULL)
return G_SOURCE_REMOVE;

icon = g_app_info_get_icon (priv->info);
if (icon == NULL)
return G_SOURCE_REMOVE;

size = gtk_image_get_pixel_size (GTK_IMAGE (priv->icon));
scale = gtk_widget_get_scale_factor (GTK_WIDGET (self));

icon_info = gtk_icon_theme_lookup_by_gicon_for_scale (gtk_icon_theme_get_default (),
icon,
size,
scale,
GTK_ICON_LOOKUP_FORCE_SIZE);
if (icon_info == NULL)
return G_SOURCE_REMOVE;

g_cancellable_cancel (priv->icon_cancel);
g_clear_object (&priv->icon_cancel);
priv->icon_cancel = g_cancellable_new ();

/* Hold a reference: a decode already in a thread cannot be taken back */
gtk_icon_info_load_icon_async (icon_info,
priv->icon_cancel,
on_icon_loaded,
g_object_ref (self));

return G_SOURCE_REMOVE;
}


static void
schedule_icon_warm (PhoshAppGridButton *self)
{
PhoshAppGridButtonPrivate *priv = phosh_app_grid_button_get_instance_private (self);

if (priv->icon_warm_id)
return;

/* Low priority: the grid is built while the shell is still starting. The
* buttons are created in display order, so the idles queue that way too. */
priv->icon_warm_id = g_idle_add_full (G_PRIORITY_LOW, warm_icon, self, NULL);
g_source_set_name_by_id (priv->icon_warm_id, "[phosh] app icon pre-warm");
}


static void
on_icon_theme_changed (PhoshAppGridButton *self)
{
PhoshAppGridButtonPrivate *priv = phosh_app_grid_button_get_instance_private (self);
GIcon *icon;

if (priv->info == NULL)
return;

/* The image is holding a surface, which GTK cannot re-resolve itself */
icon = g_app_info_get_icon (priv->info);
if (icon)
gtk_image_set_from_gicon (GTK_IMAGE (priv->icon), icon, -1);

schedule_icon_warm (self);
}


static void
phosh_app_grid_button_finalize (GObject *object)
{
PhoshAppGridButton *self = PHOSH_APP_GRID_BUTTON (object);
PhoshAppGridButtonPrivate *priv = phosh_app_grid_button_get_instance_private (self);

g_clear_handle_id (&priv->icon_warm_id, g_source_remove);
g_cancellable_cancel (priv->icon_cancel);
g_clear_object (&priv->icon_cancel);

g_clear_object (&priv->info);
g_clear_object (&priv->menu);
g_clear_object (&priv->actions);
Expand Down Expand Up @@ -549,6 +674,17 @@ phosh_app_grid_button_init (PhoshAppGridButton *self)

gtk_widget_init_template (GTK_WIDGET (self));

/* Both invalidate the surface handed to the image */
g_signal_connect_object (gtk_icon_theme_get_default (),
"changed",
G_CALLBACK (on_icon_theme_changed),
self,
G_CONNECT_SWAPPED);
g_signal_connect (self,
"notify::scale-factor",
G_CALLBACK (on_icon_theme_changed),
NULL);

gtk_popover_bind_model (GTK_POPOVER (priv->popover),
G_MENU_MODEL (priv->menu),
NULL);
Expand Down Expand Up @@ -655,6 +791,9 @@ phosh_app_grid_button_set_app_info (PhoshAppGridButton *self,
gtk_image_set_from_gicon (GTK_IMAGE (priv->icon), icon, -1);
}

/* See warm_icon() */
schedule_icon_warm (self);

gtk_widget_set_sensitive (GTK_WIDGET (self), TRUE);

if (G_IS_DESKTOP_APP_INFO (priv->info)) {
Expand Down